Showing papers by "Nanchang University published in 2014"

Wearable and Highly Sensitive Graphene Strain Sensors for Human Motion Monitoring

Abstract: Sensing strain of soft materials in small scale has attracted increasing attention. In this work, graphene woven fabrics (GWFs) are explored for highly sensitive sensing. A flexible and wearable strain sensor is assembled by adhering the GWFs on polymer and medical tape composite film. The sensor exhibits the following features: ultra-light, relatively good sensitivity, high reversibility, superior physical robustness, easy fabrication, ease to follow human skin deformation, and so on. Some weak human motions are chosen to test the notable resistance change, including hand clenching, phonation, expression change, blink, breath, and pulse. Because of the distinctive features of high sensitivity and reversible extensibility, the GWFs based piezoresistive sensors have wide potential applications in fields of the displays, robotics, fatigue detection, body monitoring, and so forth.

Molybdenum Disulfide Quantum Dots as a Photoluminescence Sensing Platform for 2,4,6-Trinitrophenol Detection

Abstract: Transition metal chalcogenides, especially molybdenum disulfide (MoS2), have recently attracted wide attention from researchers as graphene-analogous materials. However, until now, little literature has reported the synthesis of photoluminescent MoS2 materials and their applications in analytical chemistry. We herein presented a facile bottom-up hydrothermal route for the synthesis of photoluminescent MoS2 quantum dots (QDs) by using sodium molybdate and cysteine as precursors. The prepared MoS2 QDs were characterized by transmission electron microscopy, atomic force microscopy, X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, photoluminescence spectroscopy, and UV–vis spectroscopy. The MoS2 QDs were then used as photoluminescent probes to construct a photoluminescence (PL) quenching sensor for detection of 2,4,6-trinitrophenol (TNP). The TNP sensor presented a wide linear range from 0.099 to 36.5 μM with a high detection limit of 95 nM. Furthermore, the sensor displayed a high s...

Boron-Doped Graphene Quantum Dots for Selective Glucose Sensing Based on the “Abnormal” Aggregation-Induced Photoluminescence Enhancement

Abstract: A hydrothermal approach for the cutting of boron-doped graphene (BG) into boron-doped graphene quantum dots (BGQDs) has been proposed. Various characterizations reveal that the boron atoms have been successfully doped into graphene structures with the atomic percentage of 3.45%. The generation of boronic acid groups on the BGQDs surfaces facilitates their application as a new photoluminescence (PL) probe for label free glucose sensing. It is postulated that the reaction of the two cis-diol units in glucose with the two boronic acid groups on the BGQDs surfaces creates structurally rigid BGQDs–glucose aggregates, restricting the intramolecular rotations and thus resulting in a great boost in the PL intensity. The present unusual “aggregation-induced PL increasing” sensing process excludes any saccharide with only one cis-diol unit, as manifested by the high specificity of BGQDs for glucose over its close isomeric cousins fructose, galactose, and mannose. It is believed that the doping of boron can introduc...

Fruit and vegetable intake and risk of type 2 diabetes mellitus: meta-analysis of prospective cohort studies

Abstract: Objective To clarify and quantify the potential dose–response association between the intake of fruit and vegetables and risk of type 2 diabetes. Design Meta-analysis and systematic review of prospective cohort studies. Data source Studies published before February 2014 identified through electronic searches using PubMed and Embase. Eligibility criteria for selecting studies Prospective cohort studies with relative risks and 95% CIs for type 2 diabetes according to the intake of fruit, vegetables, or fruit and vegetables. Results A total of 10 articles including 13 comparisons with 24 013 cases of type 2 diabetes and 434 342 participants were included in the meta-analysis. Evidence of curve linear associations was seen between fruit and green leafy vegetables consumption and risk of type 2 diabetes (p=0.059 and p=0.036 for non-linearity, respectively). The summary relative risk of type 2 diabetes for an increase of 1 serving fruit consumed/day was 0.93 (95% CI 0.88 to 0.99) without heterogeneity among studies (p=0.477, I 2 =0%). For vegetables, the combined relative risk of type 2 diabetes for an increase of 1 serving consumed/day was 0.90 (95% CI 0.80 to 1.01) with moderate heterogeneity among studies (p=0.002, I 2 =66.5%). For green leafy vegetables, the summary relative risk of type 2 diabetes for an increase of 0.2 serving consumed/day was 0.87 (95% CI 0.81 to 0.93) without heterogeneity among studies (p=0.496, I 2 =0%). The combined estimates showed no significant benefits of increasing the consumption of fruit and vegetables combined. Conclusions Higher fruit or green leafy vegetables intake is associated with a significantly reduced risk of type 2 diabetes.

Novel image compression–encryption hybrid algorithm based on key-controlled measurement matrix in compressive sensing

Abstract: The existing ways to encrypt images based on compressive sensing usually treat the whole measurement matrix as the key, which renders the key too large to distribute and memorize or store. To solve this problem, a new image compression–encryption hybrid algorithm is proposed to realize compression and encryption simultaneously, where the key is easily distributed, stored or memorized. The input image is divided into 4 blocks to compress and encrypt, then the pixels of the two adjacent blocks are exchanged randomly by random matrices. The measurement matrices in compressive sensing are constructed by utilizing the circulant matrices and controlling the original row vectors of the circulant matrices with logistic map. And the random matrices used in random pixel exchanging are bound with the measurement matrices. Simulation results verify the effectiveness, security of the proposed algorithm and the acceptable compression performance.

Immunochromatographic assay for ultrasensitive detection of aflatoxin B₁ in maize by highly luminescent quantum dot beads.

Abstract: Highly luminescent quantum dot beads (QBs) were synthesized by encapsulating CdSe/ZnS and used for the first time as immunochromatographic assay (ICA) signal amplification probe for ultrasensitive detection of aflatoxin B1 (AFB1) in maize. The challenges to using high brightness QBs as probes for ICA are smooth flow of QBs and nonspecific binding on nitrocellulose (NC) membrane, which are overcome by unique polymer encapsulation of quantum dots (QDs) and surface blocking method. Under optimal conditions, the QB-based ICA (QB-ICA) sensor exhibited dynamic linear detection of AFB1 in maize extract from 5 to 60 pg mL–1, with a median inhibitory concentration (IC50) of 13.87 ± 0.16 pg mL–1, that is significantly (39-fold) lower than those of the QD as a signal probe (IC50 = 0.54 ± 0.06 ng mL–1). The limit of detection (LOD) for AFB1 using QB-ICA sensor was 0.42 pg mL–1 in maize extract, which is approximately 2 orders of magnitude better than those of previously reported gold nanoparticle based immunochromato...

Electron-Doping-Enhanced Trion Formation in Monolayer Molybdenum Disulfide Functionalized with Cesium Carbonate

Abstract: We report effective and stable electron doping of monolayer molybdenum disulfide (MoS2) by cesium carbonate (Cs2CO3) surface functionalization. The electron charge carrier concentration in exfoliated monolayer MoS2 can be increased by about 9 times after Cs2CO3 functionalization. The n-type doping effect was evaluated by in situ transport measurements of MoS2 field-effect transistors (FETs) and further corroborated by in situ ultraviolet photoelectron spectroscopy, X-ray photoelectron spectroscopy, and Raman scattering measurements. The electron doping enhances the formation of negative trions (i.e., a quasiparticle comprising two electrons and one hole) in monolayer MoS2 under light irradiation and significantly reduces the charge recombination of photoexcited electron–hole pairs. This results in large photoluminescence suppression and an obvious photocurrent enhancement in monolayer MoS2 FETs.

A selective USP1–UAF1 inhibitor links deubiquitination to DNA damage responses

Abstract: Deubiquitinases (DUBs) are peptidases that remove ubiquitin from post-translationally modified proteins. The identification of a selective small-molecule inhibitor of the USP1–UAF1 deubiquitination complex reveals a role for deubiquitination in regulating the DNA damage response.

The transcription factor Pou3f1 promotes neural fate commitment via activation of neural lineage genes and inhibition of external signaling pathways.

Abstract: After an egg has been fertilized, it undergoes a series of divisions to produce a ball of cells known as a blastocyst. The cells within the blastocyst are pluripotent stem cells, which have the potential to become many different types of cell. After a few days, the stem cells organize into three layers—an innermost layer called the endoderm, a middle layer of mesoderm, and an outer layer of ectoderm—that ultimately give rise to different types of tissues. The brain and nervous system are formed from cells in the neuroectoderm, which is part of the ectoderm. Now, Zhu et al. have shown that a transcription factor called Pou3f1 triggers stem cells within a region of the ectoderm to turn into neural progenitor cells, thereby generating the neuroectoderm. These neural progenitor cells then go on to become neurons and glial cells that make up the brain and nervous system. Using a virus to reduce levels of Pou3f1 in embryonic stem cells grown in a dish led to a drop in the number of stem cells that committed to neural progenitor cells. Overexpressing Pou3f1 in the stem cells restored the number of neural progenitor cells. Together these results showed that Pou3f1 is both necessary and sufficient for the conversion of embryonic stem cells into future neurons and glia. The same result was seen when embryonic stem cells containing either reduced or elevated levels of Pou3f1 were injected into 2.5-day-old mouse blastocysts, which were then implanted into surrogate females. The resulting embryos comprised some cells with normal levels of Pou3f1, and others with either too little or too much. Cells with elevated Pou3f1 mostly became neural progenitors, whereas those with reduced levels rarely did so. Gene expression studies revealed that Pou3f1 promoted the formation of neural progenitor cells by activating the expression of pro-neuronal genes inside the stem cells, and by blocking anti-neuronal pathways called Wnt/BMP signaling cascades initiated outside the cells. By revealing the two roles of Pou3f1, Zhu et al. have increased our understanding of one of the earliest stages of nervous system development. Further work is required to determine exactly how Pou3f1 exerts its effects and, in particular, whether it performs its two roles simultaneously or in sequence.

Tunable Photodeposition of MoS2 onto a Composite of Reduced Graphene Oxide and CdS for Synergic Photocatalytic Hydrogen Generation

Abstract: Recently, MoS2 as an excellent cocatalyst for hydrogen evolution reaction (HER) has attracted extensive attention. In this work, MoS2 was controllably loaded on the composite of reduced graphene oxide (rGO) and CdS (rGO/CdS) by a facile photoreduction method at different pHs. At low pH 7, MoS2 deposits on the surface of the CdS particles of the composite. However, at high pH 11, it loads on the exposed rGO. When MoS2 is on the rGO, the transfer of the photoexcited electron from CdS to rGO is compatible with the HER at MoS2 (synergic effect), whereas the transfer is incompatible with the HER when it is on the CdS (antisynergic effect). Moreover, the MoS2 deposited on the CdS decreases the photoabsorption and photoactivity of CdS, and the effect is avoided when MoS2 is on the rGO. The photocatalytic HER rate under the synergic condition is 4.3 times as high as that under antisynergic condition. This work would open a promising way to design and fabricate the efficient composite photocatalysts.

Mitochondrial dysfunction in some triple-negative breast cancer cell lines: role of mTOR pathway and therapeutic potential

Abstract: Triple-negative breast cancer (TNBC) is a subtype of highly malignant breast cancer with poor prognosis. TNBC is not amenable to endocrine therapy and often exhibit resistance to current chemotherapeutic agents, therefore, further understanding of the biological properties of these cancer cells and development of effective therapeutic approaches are urgently needed. We first investigated the metabolic alterations in TNBC cells in comparison with other subtypes of breast cancer cells using molecular and metabolic analyses. We further demonstrated that targeting these alterations using specific inhibitors and siRNA approach could render TNBC cells more sensitive to cell death compared to other breast cancer subtypes. We found that TNBC cells compared to estrogen receptor (ER) positive cells possess special metabolic characteristics manifested by high glucose uptake, increased lactate production, and low mitochondrial respiration which is correlated with attenuation of mTOR pathway and decreased expression of p70S6K. Re-expression of p70S6K in TNBC cells reverses their glycolytic phenotype to an active oxidative phosphorylation (OXPHOS) state, while knockdown of p70S6K in ER positive cells leads to suppression of mitochondrial OXPHOS. Furthermore, lower OXPHOS activity in TNBC cells renders them highly dependent on glycolysis and the inhibition of glycolysis is highly effective in targeting TNBC cells despite their resistance to other anticancer agents. Our study shows that TNBC cells have profound metabolic alterations characterized by decreased mitochondrial respiration and increased glycolysis. Due to their impaired mitochondrial function, TNBC cells are highly sensitive to glycolytic inhibition, suggesting that such metabolic intervention may be an effective therapeutic strategy for this subtype of breast cancer cells.

Recent Advances in Carbon Dioxide Capture, Fixation, and Activation by using N‐Heterocyclic Carbenes

Abstract: In the last two decades, CO2 emission has caused a lot of environmental problems. To mitigate the concentration of CO2 in the atmosphere, various strategies have been implemented, one of which is the use of N-heterocyclic carbenes (NHCs) and related complexes to accomplish the capture, fixation, and activation of CO2 effectively. In this review, we summarize CO2 capture, fixation, and activation by utilizing NHCs and related complexes; homogeneous reactions and their reaction mechanisms are discussed. Free NHCs and NHC salts can capture CO2 in both direct and indirect ways to form imidazolium carboxylates, and they can also catalyze the reaction of aromatic aldehydes with CO2 to form carboxylic acids and derivatives. Moreover, associated with transition metals (TMs), NHCs can form NHC-TM complexes to transform CO2 into industrial acid or esters. Non-metal-NHC complexes can also catalyze the reactions of silicon and boron complexes with CO2 . In addition, catalytic cycloaddition of epoxides with CO2 is another effective function of NHC complexes, and NHC ionic liquids perform excellently in this aspect.

Overexpression of long noncoding RNA HOTAIR predicts a poor prognosis in patients with cervical cancer

Abstract: The long noncoding RNA HOTAIR has been reported to be a good biomarker for poor prognosis in a variety of human cancers. However, whether HOTAIR could serve as novel biomarker to predict prognosis in cervical cancer or not is unknown. The aim of the present study was to examine the expression of HOTAIR in cervical cancers and to investigate the relationship between this lncRNA expression levels and existing clinicopathological factors and patient survival. We examined the expression of HOTAIR in 218 cervical cancer tissues and matched 218 adjacent normal tissues using quantitative real-time RT-PCR and analyzed its correlation with the clinical parameters. The results showed that HOTAIR expression in cervical cancer tissues was significantly upregulated compared with the matched nontumorous tissues (P < 0.0001). Increased HOTAIR expression was significantly correlated with FIGO stage (P < 0.0001), lymph node metastasis (P < 0.0001), depth of cervical invasion (P < 0.0001), tumor size (P = 0.006) and age (P = 0.020), but not other clinical characteristics. Moreover, cervical cancer patients with HOTAIR higher expression have shown significantly poorer overall survival (P < 0.0001) and disease-free survival (P < 0.0001) than those with lower HOTAIR expression. Univariate (P < 0.0001, HR = 4.566, 95 % CI 2.122–9.825) and multivariate (P = 0.012, HR = 2.863, 95 % CI 1.263–76.490). Cox regression analyses showed that HOTAIR expression served as an independent predictor for overall survival. our data indicate that high expression of HOTAIR is involved in cervical cancer progression and could be a potential target for diagnosis and gene therapy.

Highly Efficient Inverted Organic Solar Cells Through Material and Interfacial Engineering of Indacenodithieno[3,2‐b]thiophene‐Based Polymers and Devices

Abstract: A synergistic approach combining new material design and interfacial engineering of devices is adopted to produce high efficiency inverted solar cells. Two new polymers, based on an indacenodithieno[3,2-b]thiophene-difluorobenzothiadiazole (PIDTT-DFBT) donor–acceptor (D–A) polymer, are produced by incorporating either an alkyl thiophene (PIDTT-DFBT-T) or alkyl thieno[3,2-b]thiophene (PIDTT-DFBT-TT) π-bridge as spacer. Although the PIDTT-DFBT-TT polymer exhibits decreased absorption at longer wavelengths and increased absorption at higher energy wavelengths, it shows higher power conversion efficiencies in devices. In contrast, the thiophene bridged PIDTT-DFBT-T shows a similar change in its absorption spectrum, but its low molecular weight leads to reduced hole mobilities and performance in photovoltaic cells. Inverted solar cells based on PIDTT-DFBT-TT are explored by modifying the electron-transporting ZnO layer with a fullerene self-assembled monolayer and the MoO3 hole-transporting layer with graphene oxide. This leads to power conversion efficiencies as high as 7.3% in inverted cells. PIDTT-DFBT-TT's characteristic strong short wavelength absorption and high efficiency suggests it is a good candidate as a wide band gap material for tandem solar cells.